🌞 Designing a Three-Phase Grid-Connected Solar PV System in MATLAB/Simulink

we explore how to build a three-phase grid-connected solar PV system using MATLAB/Simulink. The model integrates solar photovoltaic (PV) generation, a boost converter with MPPT, a three-phase inverter, and control logic for grid synchronization and power delivery. Let’s dive into the step-by-step modeling procedure.

🔧 Step 1: PV Array Configuration

Start by creating a new Simulink model. Navigate to:

Simscape → Electrical → Specialized Power Systems → Renewables → Solar

Add a PV Array block to the workspace. Then, configure irradiance and temperature inputs using constant blocks:

• Irradiance: 1000 W/m²

• Temperature: 25°C

PV Panel Configuration:

• Series strings: 10

• Parallel strings: 47

• Per panel rating: 213.15 W

• Voc = 36.3 V, Vmpp = 29 V, Isc = 1.84 A, Impp = 1.35 A

• Total power: ~100 kW

⚡ Step 2: Boost Converter Design

A DC-DC boost converter is connected after the PV array to step up the voltage. Components used:

• IGBT switch

• Freewheeling diode

• DC-link capacitor: 1000 µF

• Series inductor: 1.5 mH

• Output capacitor: 3227 µF

This setup helps regulate the voltage and interfaces with the MPPT controller.

📈 Step 3: MPPT Control Using Incremental Conductance

The Maximum Power Point Tracking (MPPT) algorithm is implemented using a User-Defined Function in Simulink.

Algorithm Overview:

• Calculates ΔV and ΔP (change in voltage and power)

• Adjusts the reference voltage (Vref) accordingly

• Keeps track of previous and current voltage/power states

• Maintains Vref within defined max and min limits (e.g., 0 to 363 V)

• Loop executes continuously to track the maximum power point

The control output from this function modulates the duty cycle for the boost converter.

🔁 Step 4: PWM Pulse Generation for IGBT

The MPPT output is fed into a PI controller (P = 0.005, I = 0.001).This is compared against a triangular waveform using a relational operator to produce gate pulses for IGBT switching.

This forms the pulse generator for the boost converter.

🔌 Step 5: Subsystem Creation for PV and Boost Converter

The PV panel, MPPT controller, and boost converter components are grouped into a subsystem labeled:

• PV+MPPT+Boost ConverterThis encapsulates the DC generation and voltage regulation side of the model.

🔄 Step 6: Three-Phase Inverter Design

A three-phase inverter is built using six IGBT switches arranged in a standard topology.

Additional Components:

• RL filter for each phase (L = 1 mH, R = 1e-3 Ω)

• RC filter to smooth output voltage

• Three-phase grid source: 400V, 50Hz

🔍 Step 7: Voltage and Current Measurements

Voltage and current at various points are measured using:

• Three-phase voltage/current measurement blocks

• Display blocks for real-time observation

These help in analyzing inverter output and grid interfacing.

🔁 Step 8: Reference Frame Transformation (ABC → αβ → dq)

To facilitate grid synchronization, signals are converted:

• ABC → αβ using Clarke transformation

• αβ → dq using Park transformation

Control Logic:

• Voltage and current components (Vd, Vq, Id, Iq) are extracted.

• These are compared with set references using PI controllers to regulate power flow and maintain grid standards.

🌀 Step 9: Grid Synchronization and Control

The outer control loop maintains DC-link voltage at 700V, while the inner loop regulates Id and Iq to achieve desired power injection.

The final dq components are converted back to ABC using an inverse transformation and used for PWM generation.

PWM pulses are generated using repeating sequence (triangular wave) and comparator blocks to drive inverter IGBTs.

📊 Step 10: Simulation and Analysis

The model is simulated under varying irradiance levels.

Observations:

• At 1000 W/m², output power ≈ 100 kW

• At 500 W/m², power drops to ≈ 50 kW

• The system dynamically tracks the maximum power point and regulates inverter output effectively.

✅ Conclusion

This MATLAB/Simulink model provides a comprehensive simulation of a three-phase grid-tied solar PV system with:

• MPPT control

• Boost converter

• Inverter and filter design

• dq transformation-based current control

• Real-time monitoring and power tracking

It serves as a strong foundation for further research or educational simulation of renewable energy integration into the grid.